function monthLength(year, month)
{
  var date = new Date();
  date.setFullYear(year, month, 32);
  return 32 - date.getDate();
};

Date.prototype.getMonthDays = function(month) {
	var year = this.getFullYear();
	if (typeof month == "undefined") {
		month = this.getMonth();
	}
	if (((0 == (year%4)) && ( (0 != (year%100)) || (0 == (year%400)))) && month == 1) {
		return 29;
	} else {
		return Date._MD[month];
	}
};